JP2019009502A - Radio communications system, radio relay device, and radio relay program - Google Patents

Abstract

To provide a radio communications system that determines a radio relay device which becomes a connection destination at high efficiency.SOLUTION: A radio communications system includes: a radio communication device; and a radio relay device that relays a connection request to a network of the radio communication device. When the radio communication device transmits an adjacent search packet for searching the radio relay device as a connection destination to the circumference, and receives a response packet corresponded to the adjacent search packet from the radio relay device, the radio communication device selects the radio relay device as the communication destination on the basis of an index value in regards to a communication quality used for determination whether the radio relay device in a transmission destination of the response packet is selected as the connection destination. When the radio relay device manages the index value of the radio relay device adjacent to itself, and receives the adjacent search packet from the radio communication device, the radio relay device calculates a response stand-by time until the transmission of the response packet by using the own index value and the index value of the adjacent radio relay device, and transmits the response packet to the radio communication device after the lapse of the response stand-by time calculated.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a wireless communication system, a wireless relay device, and a wireless relay program, and can be applied to, for example, a wireless multi-hop network.

  In a wireless network system including a plurality of wireless communication devices (hereinafter also referred to as “nodes”) and a management device that manages each node, when each node cannot communicate directly with the management device, another node cannot communicate directly Instead, a form of a multi-hop network that relays communication may be adopted. This form of multi-hop network enables nodes at a long distance to communicate with the management device.

  When a node newly joining the multi-hop network (hereinafter also referred to as a “participating node”) joins (joins) the network and cannot communicate directly with the management apparatus, the node joins the network joining request packet. Nodes to be relayed (hereinafter also referred to as “parent nodes”) are selected from nodes that have joined the network. In order to select such a parent node, the participating node broadcasts a packet (hereinafter also referred to as “neighboring node search packet”) for searching its own peripheral node (hereinafter also referred to as “neighboring node”). . The adjacent node that has received the packet returns a response packet to the participating node. At this time, if the transmission timing of the response packet of the adjacent node overlaps with another adjacent node, the packets collide and the participating nodes cannot receive the response packet. For this reason, in order to avoid collision, the adjacent node waits for a random time after receiving the adjacent node search packet and then transmits the response packet.

  By the way, there are various methods for selecting an optimal parent node. For example, it may be possible to select a node having the highest received signal strength (RSSI value) of a received packet. The participating node collects response packets of all neighboring nodes and selects a parent node from among the response packets, thereby determining an optimal parent node. However, in order to collect response packets of all neighboring nodes, the participating node needs to wait for a maximum waiting time that can be selected in consideration of the random waiting time of the response packet. Here, since the response packet has a higher probability of collision as the number of adjacent nodes increases, it is necessary to suppress the collision probability to a certain level or less. Therefore, the maximum value of the random waiting time should be set longer considering the case where the number of adjacent nodes is large.

  As described above, since a participating node requires a lot of time to select a parent node, it becomes a problem that the time until the network subscription is prolonged.

  By the way, the techniques described in Patent Documents 1 and 2 are techniques relating to an optimal method for selecting a parent node in a multi-hop network. In the techniques described in Patent Documents 1 and 2, the participating node transmits information on the adjacent node transmitted from the adjacent node (the current number of child nodes, the number of hops to the management device, and the RTT (Round Trip TiMe to the management device). ) Etc.) and the adjacent node considered to be optimal is selected as the parent node.

  Further, in Patent Document 2, each node calculates a packet loss rate and an SN ratio (Signal-to-Noise ratio) from a communication history with an adjacent node even after joining the network, and determines an optimal parent node from these information. Change dynamically.

JP 2009-302694 A Special table 2011-523830 gazette

  However, both of the techniques described in Patent Documents 1 and 2 are techniques related to an index for selecting an optimal parent node, and wait for response packets from all neighboring nodes in order to select an optimal parent node. It is assumed that.

  Therefore, the selection time of the parent node greatly depends on the random waiting time of the response packet transmitted by the adjacent node.

  Therefore, there is a demand for a wireless communication system, a wireless relay device, and a wireless relay program that can efficiently determine a wireless relay device to be a connection destination and join a wireless network at an early stage.

  A first aspect of the present invention is a wireless communication system including a wireless communication device that requests connection to a network and a plurality of wireless relay devices that relay connection requests to the network. (1) The wireless communication device includes: (1-1) Neighboring node search means for transmitting an adjacent search packet for searching for the wireless relay device as a connection destination from among the plurality of wireless relay devices to the surrounding network; (1- 2) When a response packet for the adjacent search packet is received from each wireless relay device, an index value relating to communication quality used for determining whether to select the wireless relay device that is the transmission source of the response packet as a connection destination And (2) the wireless relay device is configured to select (2-1) the wireless relay device as a connection destination from among the wireless relay devices. Neighboring node information management means for managing the index value of the radio relay apparatus adjacent to the radio relay apparatus; and (2-2) receiving the neighbor search packet from the radio communication apparatus, the radio adjacent to the index value of the radio relay apparatus. A response waiting time calculating means for calculating a response waiting time until the response packet is transmitted using the index value of the relay apparatus; and (2-3) after the response waiting time calculated by the response waiting time calculating means has elapsed. And response packet transmission means for transmitting the response packet to the wireless communication device.

  A second aspect of the present invention is a wireless relay device in a wireless communication system having a wireless communication device that requests connection to a network and a plurality of wireless relay devices that relay the connection request to the network. Neighboring node information management means for managing an index value relating to communication quality of the wireless relay device adjacent to the wireless relay device; and (2) the wireless relay device as a connection destination among the plurality of wireless relay devices from the wireless communication device. When an adjacent search packet for searching is received, a response waiting time until a response packet for the adjacent search packet is transmitted is calculated using its own index value and the index value of the adjacent radio relay apparatus. A response waiting time calculating means; and (3) transmitting the response packet to the wireless communication apparatus after the response waiting time calculated by the response waiting time calculating means has elapsed. And having a response packet transmitting unit that.

  A radio relay program according to a third aspect of the present invention is mounted on a radio relay apparatus in a radio communication system having a radio communication apparatus that requests connection to a network and a plurality of radio relay apparatuses that relay connection requests to the network. (1) an adjacent node information management means for managing an index value relating to communication quality of the wireless relay device adjacent to itself, and (2) a connection destination from the wireless communication device among the plurality of wireless relay devices. When an adjacent search packet for searching for the wireless relay device is received, a response packet for the adjacent search packet is transmitted using its own index value and the index value of the adjacent wireless relay device. A response waiting time calculating means for calculating the response waiting time, and (3) after the response waiting time calculated by the response waiting time calculating means has elapsed, A response packet, characterized in that to function as a response packet transmitting means for transmitting to the wireless communication device.

  ADVANTAGE OF THE INVENTION According to this invention, the radio relay apparatus used as a connection destination can be determined efficiently and it can participate in a radio network at an early stage.

It is a block diagram shown about the functional structure of the radio | wireless communication apparatus which concerns on embodiment. It is a block diagram shown about the example of the whole structure of the radio | wireless communications system which concerns on embodiment. It is a block diagram shown about the functional structure of the management apparatus which concerns on embodiment. It is a flowchart which shows operation | movement (operation | movement at the time of network subscription) of the radio | wireless communication apparatus (participation node) which concerns on embodiment. It is a flowchart which shows operation | movement (operation | movement at the time of reception of an adjacent search packet) of the radio | wireless communication apparatus (parent candidate node) which concerns on embodiment. It is a flowchart which shows the operation | movement (transmission waiting time calculation operation | movement of a response packet) of the radio | wireless communication apparatus (parent candidate node) concerning embodiment. It is explanatory drawing which shows the adjacent search packet transmission interval divided | segmented into the slot unit which concerns on embodiment. It is a block diagram (the 1) shown about the functional structure of the radio | wireless communication apparatus which concerns on a modification. It is a block diagram (the 2) shown about the functional structure of the radio | wireless communication apparatus which concerns on a deformation | transformation form.

(A) Embodiments Hereinafter, main embodiments of a wireless communication system, a wireless relay device, and a wireless relay program according to the present invention will be described in detail with reference to the drawings.

(A-1) Configuration of Embodiment (A-1-1) Overall Configuration FIG. 2 is a block diagram illustrating an example of the overall configuration of the wireless communication system 1 according to the embodiment.

  First, the configuration of the wireless communication system 1 will be described.

  In the wireless communication system 1, a management device 20 that manages the wireless communication devices 10 (10-1 to 10-n) and a plurality of wireless communication devices 10 that perform wireless communication are arranged. The number of devices arranged in the wireless communication system 1 is not limited, but in the wireless communication system 1 of this embodiment, one management device 20 and a plurality of wireless communication devices 10 (10-1 to 10-1). 10-n) is assumed to be arranged.

  Further, in the wireless communication system 1, it is assumed that a multi-hop network is configured by nodes including the management device 20 and the wireless communication devices 10-1 to 10-n. Hereinafter, each wireless communication device 10 is also referred to as a “node” constituting a multi-hop network. A node that intends to participate in the network of the wireless communication system 1 is referred to as a “participating node”, and a node that relays the participation request packet of the participating node to the management device 20 is referred to as a “parent node”. An adjacent node that can directly communicate with a certain node is referred to as an “adjacent node”. The communication method (communication medium) between the devices (between nodes) in the wireless communication system 1 is not limited. For example, various wireless LAN interface communication methods can be applied.

  Next, features of the wireless communication system 1 of this embodiment will be described.

  In this embodiment, adjacent nodes (parent candidate nodes) existing around the participating node use the path quality and adjacent node information to transmit a response packet (response packet for an adjacent search packet transmitted by the participating node). To decide. “Path quality” indicates communication quality between itself (wireless communication device 10) and management device 20 (base station). For example, a link quality value (for example, RSSI) on a route to the base station. Value, a value calculated based on the packet loss rate). The “neighboring node information” is information including the address of the adjacent node of itself and path quality (and may include the number of hops to the base station). The adjacent node information is generated from a control packet periodically transmitted by each node, for example.

  As the response packet transmission waiting time, a short waiting time is set when the path quality is good, and a long waiting time is set when the path quality is bad. However, when the transmission waiting time is set in this way, there is a possibility that response packets may collide if the number of adjacent nodes with good path quality is large. Therefore, the transmission waiting time selected by the node with good path quality is further determined using the adjacent node information. Specifically, in order to avoid response packet collision, the larger the number of adjacent nodes with good path quality, the wider the transmission waiting time that can be selected.

  When the path quality of the response packet transmission source node (parent candidate node) and the path quality obtained by adding the link quality of itself and the transmission source node are equal to or higher than the threshold, the participating node selects the node as the parent node.

(A-1-2) Detailed Configuration of Radio Communication Device Next, the internal configuration of the radio communication device 10 will be described.

  FIG. 1 is a block diagram illustrating a functional configuration of the wireless communication apparatus. In FIG. 1, the wireless communication device 10 includes a communication unit 11, a processing unit 12, an adjacent node information management unit 13, a response waiting time calculation unit 14, and a parent node selection unit 15.

  For example, the wireless communication device 10 may be constructed by installing a program in a computer having a processor and a memory. The wireless communication device 10 may be partially or entirely configured using hardware (for example, a dedicated semiconductor chip or an electric circuit).

  The wireless communication device 10 of this embodiment shows a configuration example having a function as a participating node and a function as a parent candidate node (wireless relay device), but is not limited to this. The parent node selection unit 15 may be omitted if it only serves as a device.

  The communication unit 11 is a communication interface for accessing a multihop network. For example, when receiving a packet transmission request from the processing unit 12 described later, the communication unit 11 includes a unit that transmits a packet to the management device 20 or another wireless communication device 10. In addition, when the communication unit 11 cannot directly transmit to the communication partner, the communication unit 11 transmits a packet via another wireless communication device 10. Note that the communication unit 11 can apply various routing methods as a relay method to another wireless communication device 10. For example, the communication unit 11 can apply a routing method such as AODV (Ad hoc On-Demand Distance Vector), RPL (IPv6 Routing Protocol for Low-Power and Lossy Networks) as a routing method. In addition, the communication unit 11 includes means for measuring an RSSI value when receiving a packet.

  The processing unit 12 generates packets for searching for adjacent wireless communication devices 10 that are candidates for a parent node (hereinafter also referred to as “adjacent search packets”) at regular intervals before joining the network. Requests the unit 11 to transmit the adjacent search packet. When receiving the response packet for the adjacent search packet from the communication unit 11, the processing unit 12 requests the parent node selection unit 15 to make a parent selection determination. When the processing unit 12 receives the address of the parent node selected from the parent node selection unit 15, the processing unit 12 generates a participation request packet addressed to the management device 20 with the parent node as a relay destination, and transmits the packet to the communication unit 11. Request.

  On the other hand, when the processing unit 12 receives a neighbor search packet from the communication unit 11 after joining the network, the processing unit 12 acquires a response waiting time from the response waiting time calculating unit 14. Then, after waiting for the acquired waiting time, the processing unit 12 generates a response packet and requests the communication unit 11 to transmit the response packet. The response packet includes an index value that is referred to in order to select a parent node (in this embodiment, its own path quality value and an RSSI value when an adjacent search packet is received). Further, when receiving the control packet from the communication unit 11, the processing unit 12 requests the adjacent node information management unit 13 to register the adjacent node information.

  The parent node selection unit 15 includes means for selecting the wireless communication device 10 that is a parent node from the received response packet. When receiving a parent selection determination request from the processing unit 12, the parent node selection unit 15 determines whether or not to select a transmission source node of the response packet as a parent. As a result of the determination, if the parent is not selected, the parent node selection unit 15 stores the response packet information. However, if the parent is not selected before the next adjacent search packet transmission, the parent is selected from the stored information of the response packet. When the parent node selection unit selects the parent node, the parent node selection unit notifies the processing unit 12 of the selected parent node.

  The adjacent node information management unit 13 has means for holding and managing adjacent node information. When the adjacent node information management unit 13 receives the registration request for adjacent node information from the processing unit 12, the adjacent node information management unit 13 extracts the source address and path quality information from the packet and manages, for example, the address of the adjacent node and the path quality in association with each other. To be held in the table. The adjacent node information management unit 13 updates the path quality of the table when the control packet is from a registered node. Further, the adjacent node information management unit 13 may consider that a node that has not received a control packet for a certain period of time has left the network and delete it from the table.

  The response waiting time calculating unit 14 has means for calculating a waiting time until a response packet is transmitted for an adjacent search packet of a participating node. When receiving a response waiting time calculation request from the processing unit 12, the response waiting time calculating unit 14 acquires adjacent node information from the adjacent node information managing unit 13, and calculates a response waiting time. The response waiting time calculation unit 14 notifies the processing unit 12 of the calculated waiting time.

(A-1-3) Detailed Configuration of Management Device Next, the internal configuration of the management device 20 will be described.

  FIG. 3 is a block diagram illustrating a functional configuration of the management apparatus. Each configuration of the management device 20 (each configuration excluding the parent node selection unit 15) is the same as that of the wireless communication device 10 shown in FIG. However, since the contents of the processing unit are different, this difference will be mainly described.

  In addition to the function of the processing unit 12 of the wireless communication device 10, the processing unit 22 of the management device 20 generates a response packet (participation approval packet) for the participation request packet when receiving the participation request packet of the participating node from the communication unit 11. And means for requesting the communication unit 11 to transmit the packet.

(A-2) Operation | movement of embodiment Next, operation | movement of the radio | wireless communications system 1 of embodiment which has the above structures is demonstrated.

  In the following, until the new wireless communication device 10 (participating node) selects a parent node (parent node) from neighboring nodes (parent candidate nodes of nodes that have already joined the network) and participates in the multi-hop network. The operation of each apparatus will be described with reference to FIGS. The operation of the participating node is step S101 (FIG. 4) described later. The operation of the adjacent node (parent candidate node) is step S102 (FIG. 5) and step S103 (FIG. 6) described later. Further, the operation of the management apparatus 20 is step S104. In the following, it is assumed that the participating node is one of the wireless communication devices 10 (10-1 to 10-n) before joining the network of the wireless communication system 1. Further, the adjacent nodes (parent candidate nodes) are the wireless communication devices 10 (10-1 to 10-n) that have joined the network of the wireless communication system 1 that exists within the range in which the packets broadcast by the participating nodes can be received. It shall be either.

[Step S101: Operation of Participating Node]
FIG. 4 is a flowchart illustrating an operation (operation when joining a network) of the wireless communication device (participating node) according to the embodiment.

  After the activation, the participating node (processing unit 12) broadcasts the generated adjacent search packet via the communication unit 11 in order to search for an adjacent node (parent candidate node) (S101-1 and S101-2). At this time, the processing unit 12 sets the timer only for the time until the next adjacent search packet is transmitted (hereinafter referred to as “adjacent search packet transmission interval”).

  The processing unit 12 performs the processes in and after step S101-4, which will be described later, until the adjacent search packet transmission interval elapses (notification of the set timer timeout). The process of step S101-7 is performed (S101-3).

  When the processing unit 12 receives a response packet from any of the adjacent nodes via the communication unit 11, the received response packet information (at least the path quality value of the response packet, the information of the RSSI value when the adjacent search packet is received) And the RSSI value at the time of receiving the response packet is notified to the parent node selection unit 15 (S101-4). When receiving the notification of response packet reception, the parent node selection unit 15 first determines whether or not to select the parent node, and first transmits it from the RSSI value when the adjacent search packet is received and the RSSI value when the response packet is received. The link quality value with the original node (adjacent node) is calculated. The link quality value is, for example, a value obtained by converting two RSSI values into a link quality value and multiplying them. The conversion from the RSSI value to the link quality value is performed by giving one link quality value to the range of the RSSI value. For example, when the RSSI value is −60 dBm or more, the best (large) value is given as the link quality value, and when it is less than −60 dBm and more than −80 dBm, the second best value is given. Give the worst (smallest) value, etc. Next, the parent node selection unit 15 adds the obtained link quality value and the path quality value of the response packet, and calculates the path quality value from itself (participating node) to the management apparatus 20.

  Then, the parent node selection unit 15 compares the calculated path quality value with a preset threshold value (S101-5). The parent node selection unit 15 selects the transmission source node as the parent node when the path quality value is equal to or higher than the threshold value, and stores the response packet information therein when the path quality value is lower than the threshold value (step S101- described later). 8). When the parent node is selected, the parent node selection unit 15 notifies the processing unit 12 of the address of the selected parent node.

  When the processing unit 12 receives the notification of the parent node address from the parent node selection unit 15 by the processing of the above-described step S101-5 (or processing of step S101-8 described later), the participation request with the address as a relay destination A packet is generated, and the packet is transmitted via the communication unit (S101-6).

  On the other hand, when the notification of the parent node address is not received from the parent node selection unit 15 during the adjacent search packet transmission interval, the processing unit 12 notifies the parent node selection unit 15 of the parent node selection request.

  When receiving the parent node selection request from the processing unit 12, the parent node selection unit 15 confirms whether one or more response packets have been received so far (in other words, whether the information of the response packet is stored internally) ( S101-7). When the parent node selection unit 15 has not received one response packet, the parent node selection unit 15 notifies the processing unit 12 of retransmission of the adjacent search packet (again, a series of processing is executed from step S101-2).

  If one or more response packets have been received by the processing in step S101-7 described above, the parent node selection unit 15 selects the selection source node of the response packet with the best path quality value as the parent node, and selects it. The address of the parent node is notified to the processing unit 12 (S101-8). Since the processing after the notification is the same as the processing in step S101-6 described above, a description thereof will be omitted.

  Then, when the communication unit 11 receives the participation approval packet for the participation request packet transmitted by the process of S101-6, the communication unit 11 notifies the processing unit 12 to that effect. After the notification, the processing unit 12 shifts from the participating node to the operation of the parent candidate node.

[Step S102: Operation of Parent Candidate Node]
FIG. 5 is a flowchart illustrating the operation of the wireless communication device (parent candidate node) according to the embodiment (operation when receiving an adjacent search packet).

  When the communication unit 11 of the parent candidate node receives the adjacent search packet, the communication unit 11 notifies the processing unit 12 of information on the adjacent search packet (S102-1). The processing unit 12 notifies the RSSI value when the adjacent search packet is received, and requests the response waiting time calculation unit 14 to calculate the response waiting time.

  The response waiting time calculation unit 14 executes a process of step S103 described later and calculates a response waiting time (S102-2). The response waiting time calculation unit 14 notifies the processing unit 12 of the calculated response waiting time.

  When receiving the response waiting time, the processing unit 12 waits for the received response waiting time (S102-3).

  The processing unit 12 monitors whether the response waiting time has elapsed. If the response waiting time has elapsed, the processing unit 12 generates a response packet and requests the communication unit 11 to transmit the response packet (S102-4).

  The communication unit 11 transmits a response packet to the participating node (S102-5).

[Step S103: Operation of Parent Candidate Node (Response Waiting Time Calculation Operation)]
FIG. 6 is a flowchart showing the operation (response packet transmission waiting time calculating operation) of the wireless communication apparatus (parent candidate node) according to the embodiment.

  Steps S103-1 to S103-5 described later are processes for calculating N (the number of adjacent nodes including itself satisfying the path quality) used in the expression (2) described later. The obtained N is used in the process of step S103-6 described later (calculating equation (2)). And a response waiting time is calculated | required using (2) Formula calculated by the process of step S103-7-S101-10. Hereinafter, details of the processing of each step will be described.

  The response waiting time calculation unit 14 initializes N (sets N to “0”) (S103-1).

  The response waiting time calculating unit 14 converts the RSSI value at the time of receiving the adjacent search packet into a link quality value, adds the obtained link quality value and the own path quality value, and compares it with a threshold value (S103-2).

  When the result (comparison result) of the above-described step S103-2 is equal to or greater than the threshold, the response waiting time calculation unit 14 regards itself as a node that satisfies the path quality for the participating node, and increments N (S103- 3). On the other hand, when the comparison result is less than the threshold, the response waiting time calculation unit 14 regards itself as a node that does not satisfy the path quality for the participating node (no particular processing is performed on N).

  The response waiting time calculation unit 14 acquires the path quality values of all the adjacent nodes from the adjacent node information management unit 13, and calculates the number of adjacent nodes that is equal to or greater than the threshold value among the acquired path quality values (S103- 4).

  The response waiting time calculating unit 14 adds N to the number of adjacent nodes that is equal to or greater than the threshold obtained in the process of step S103-4 described above (S103-5).

Subsequently, the response waiting time calculation unit 14 is based on N that is the number of adjacent nodes including itself that satisfies the path quality and information on whether or not itself satisfies the path quality (determination result in step S103-2 described above). Calculate the response waiting time. FIG. 7 is an explanatory diagram showing adjacent search packet transmission intervals divided into slot units according to the embodiment. As shown in FIG. 7, the response waiting time is determined by dividing the adjacent node search packet transmission interval of the participating nodes into slots SL and selecting one of the slots SL. The length per slot SL is a constant. Of the divided slots SL, the first half slot SL is selected by a node satisfying the path quality, and the second half slot SL is selected by a node not satisfying the path quality. For example, FIG. 7A shows the state of the slot SL when there are few adjacent nodes satisfying the path quality, and the slots SL1 to SL3 are slots (first half slots) selected by the node satisfying the path quality. Slots SL4 to SL9 are slots (second half slots) selected by nodes that do not satisfy the path quality. On the other hand, FIG. 7B shows the state of the slot SL when there are many adjacent nodes that satisfy the path quality, and the slots SL1 to SL6 are slots (first half slots) selected by the node that satisfies the path quality. Slots SL7 to SL8 are slots (second half slots) selected by nodes that do not satisfy the path quality. Of the divided slots, the boundary between the slot selected by the node with good path quality and the slot selected by the bad node is calculated based on, for example, equation (1).

  In the equation (1), slot is the number of slots, and N is the number of adjacent nodes that satisfy the path quality including itself as described above. P in the expression (1) is a case where a certain node satisfying the path quality and other N−1 neighboring nodes satisfying the path quality select one slot from the slot at random and transmit a response packet. The probability that the node can transmit a response packet without colliding with a response packet of another node (referred to as a response packet transmission success rate) is shown. If the response packet transmission success rate to be satisfied as a network system is predetermined, the slot boundary is calculated so as to satisfy the response packet transmission success rate P.

That is, when the response packet transmission success rate to be satisfied is Pgiven, the minimum slot that satisfies the following equation (2) is the slot boundary.

  When the response waiting time calculating unit 14 determines that the node satisfies the path quality by the process in step S103-2 described above, the response waiting time calculating unit 14 randomly selects one slot from the slot SL in the first half of the boundary obtained by the equation (2). Select (S103-7, S103-8). On the other hand, when the response waiting time calculation unit 14 determines that the node does not satisfy the path quality by the process of step S103-2 described above, the response waiting time calculation unit 14 randomly selects one slot from the latter half slot SL (S103-9). ).

  The response waiting time calculation unit 14 converts the selected slot SL into a unit of time (selected slot × 1 slot size) and notifies the processing unit 12 (S103-10). For example, when the response waiting time calculation unit 14 has good path quality and selects the slot SL2 from the first half slot SL (SL1 to SL3) in FIG. 7A, the “1 slot size” is set to “2”. A value obtained by multiplying by is calculated as a response waiting time (notifies the processing unit 12 of the calculated response waiting time).

[Step S104: Operation of Management Device]
When the communication unit 11 of the management device 20 receives the participation request packet from the wireless communication device 10, the communication unit 11 notifies the processing unit 22 accordingly. The processing unit 22 generates a participation approval packet and transmits the packet via the communication unit 11.

(A-3) Effects of the embodiment According to this embodiment, the following effects are obtained.

  The wireless communication device 10 (parent candidate node) uses the response waiting time calculation unit 14 to calculate the transmission timing of the response packet for the adjacent search packet of the participating node using the path quality information and the adjacent node information. In other words, by using the path quality information and setting the transmission timing so that the response candidate packet is returned early for the parent candidate node with good path quality, the participating node first receives the response packet from the parent candidate node with good path quality. Can be received.

  In addition, by using the adjacent node information and dynamically changing the response waiting time selection width according to the number of adjacent nodes with good path quality, the parent candidate node can transmit an appropriate transmission timing that does not depend on the node installation density. Can be calculated. For example, when there are a large number of neighboring nodes with good path quality, the response waiting time selection range is wide, so that collision of response packets is avoided, and participating nodes receive response packets with high probability from good parent candidate nodes. can do. Furthermore, the participating node can reduce the time required for parent node selection by using the path quality information in the received response packet and selecting the parent node when the path quality is equal to or higher than the threshold.

  In this embodiment, by setting the transmission timing of the response packet for the adjacent search packet in units of slots, the throughput can be improved as compared to setting the response timing in units of non-slots.

(B) Other Embodiments The present invention is not limited to the above-described embodiments, and may include modified embodiments as exemplified below.

  (B-1) In the above embodiment, an example in which the path quality is used as a determination index of a good parent candidate node has been described, but the present invention is not limited to this. For example, the wireless communication device 10 can use the link quality value per hop obtained by dividing the path quality value by the number of hops. Since the path quality is a value that also depends on the number of hops, a parent candidate node with a larger number of hops is less likely to be a better parent candidate node. The wireless communication apparatus 10 can obtain a determination index that does not depend on the number of hops by using the link quality per hop.

  (B-2) In the above embodiment, when the parent candidate node receives an adjacent search packet of a plurality of participating nodes, an example is shown in which a response packet is transmitted to each node. However, the present invention is limited to this. is not. For example, the wireless communication device 10 (parent candidate node) may collectively transmit a plurality of adjacent search packets as one response packet. In this case, the parent candidate node stores the RSSI value of the received adjacent search packet together with the transmission source address during the response waiting time, and stores the RSSI value and the transmission source address stored in the response packet. List all pairs and broadcast. The parent candidate node can reduce the traffic volume by sending the response packets together. Also, the method for calculating the response waiting time when receiving a plurality of adjacent search packets is not limited, and the method for selecting the response waiting time of the first received adjacent search packet or the shortest time among the calculated response waiting times is selected. Various methods such as methods can be applied.

  (B-3) In the above embodiment, an example of determining whether or not it is a good parent candidate node using a constant threshold value has been shown. However, the present invention is not limited to this. For example, according to the number of adjacent nodes You may judge using the threshold value which changes dynamically. For example, it is assumed that the greater the number of adjacent nodes, the higher the node density of the network and the greater the number of good parent candidate nodes. In such a case, collision of response packets can be prevented by setting the threshold value more strictly. In addition to preventing, participating nodes can select a better parent node.

  (B-4) In the above embodiment, the operation of the wireless communication device 10 when participating in the network has been described as an example. However, the present invention is not limited to this. For example, a relay path for relaying in multihop from the wireless communication device 10 to the management device 20 may be constructed using the mechanism (technical idea) of the above embodiment.

  (B-5) In the above embodiment, it is assumed that one management apparatus 20 exists in the wireless communication system 1, but the present invention is not limited to this. For example, the wireless communication system 1 may be a wireless network system configured such that one or more predetermined wireless communication devices 10 accept connections from other wireless communication devices 10 without the management device 20 being installed. In this case, the wireless communication device 10 (parent candidate node) that accepts the connection may be configured such that the processing unit 12 and the parent node selection unit 15 are removed (configuration in FIG. 8). The response waiting time calculation unit 14 in FIG. 8 also has the role of the processing unit 12 in FIG. The wireless communication device 10 (participating node) that requests connection may have a configuration (configuration in FIG. 9) in which the response waiting time calculation unit 14 and the adjacent node information management unit 13 are removed from the configuration in FIG.

  DESCRIPTION OF SYMBOLS 1 ... Wireless communication system, 10 (10-1-10-n) ... Wireless communication apparatus, 11 ... Communication part, 12, 22 ... Processing part, 13 ... Neighboring node information management part, 14 ... Time calculation part, 15 ... Parent Node selection unit, 20 ... management device, SL (SL1 to SL9) ... slot.

Claims (9)

In a wireless communication system having a wireless communication device that requests connection to a network and a plurality of wireless relay devices that relay connection requests to the network,
The wireless communication device
An adjacent node search means for transmitting an adjacent search packet for searching for the wireless relay device as a connection destination from among the plurality of wireless relay devices toward the surrounding network;
When a response packet for the adjacent search packet is received from each wireless relay device, based on an index value related to communication quality used to determine whether to select the wireless relay device that is the transmission source of the response packet as a connection destination, Connection destination selection means for selecting the wireless relay device as a connection destination from among the wireless relay devices;
The wireless relay device is
Adjacent node information management means for managing the index value of the radio relay apparatus adjacent to itself;
When the neighbor search packet is received from the wireless communication device, a response wait time for calculating a response waiting time until the response packet is transmitted is used by using the index value of the wireless communication device and the index value of the adjacent wireless relay device. Time calculation means;
A wireless communication system, comprising: response packet transmitting means for transmitting the response packet to the wireless communication apparatus after the response waiting time calculated by the response waiting time calculating means has elapsed. The response waiting time calculation means compares the index value of itself with a threshold value, and according to the comparison result, the response waiting time calculation unit has a short response waiting time within a period of two minutes that can be taken as the response waiting time. Select either the first half of the response waiting time or the second half of the response waiting time that is the range of the long response waiting time, and within the selected first half of the response waiting time or the second half of the response waiting time, Calculate the response waiting time,
The index value of each of the wireless relay devices adjacent to itself and the threshold are compared, the number of the wireless relay devices with good communication quality equal to or higher than the threshold is counted, and the number of the wireless relay devices with good communication quality is The larger the number, the longer the response waiting time in the first half, the response waiting time in the second half is shortened by the length, and the fewer the number of wireless relay devices with good communication quality, the shorter the response waiting time in the first half. The wireless communication system according to claim 1, wherein the response waiting time in the latter half is increased by the shortened amount.   The response waiting time of the first half is determined within a range satisfying a predetermined success rate at which the response packet transmitted by itself does not collide with the response packet transmitted by another wireless relay device. The wireless communication system according to claim 2.   The response waiting time calculating means calculates the response waiting time by selecting the response waiting time in the slot unit from the response waiting time in the first half and the response waiting time in the latter half divided into slots. 3. The wireless communication system according to 3.   The wireless communication system according to claim 2, wherein the threshold value changes according to the number of adjacent wireless relay devices.   If the adjacent search packet is received from one or more other wireless communication devices until the calculated response waiting time elapses, one response packet for all the received adjacent search packets The wireless communication system according to claim 2, wherein the wireless communication system transmits the data as a group to the network. The connection destination selection unit selects the wireless relay device that is the transmission source of the response packet as a connection destination when the index value corresponding to the wireless relay device that is the transmission source of the response packet is equal to or greater than the threshold value. ,
When the connection destination is not selected within a predetermined search period, the connection destination selection means receives the index value corresponding to the wireless relay device that is the transmission source of the response packet received within the search period. The wireless communication system according to any one of claims 2 to 6, wherein a best value is searched from among the wireless relay devices, and the wireless relay device having the best index value is selected as a connection destination. A wireless relay device in a wireless communication system having a wireless communication device that requests connection to a network and a plurality of wireless relay devices that relay connection requests to the network,
Adjacent node information management means for managing an index value related to communication quality of the radio relay apparatus adjacent to itself;
When an adjacent search packet for searching for the wireless relay device as a connection destination among a plurality of the wireless relay devices is received from the wireless communication device, the index value of the wireless relay device adjacent to its own index value A response waiting time calculating means for calculating a response waiting time until a response packet for the adjacent search packet is transmitted, and
A wireless relay device comprising: response packet transmitting means for transmitting the response packet to the wireless communication device after the response waiting time calculated by the response waiting time calculating means has elapsed. A computer mounted on a wireless relay device in a wireless communication system having a wireless communication device requesting connection to a network and a plurality of wireless relay devices relaying the connection request to the network;
Adjacent node information management means for managing an index value related to communication quality of the radio relay apparatus adjacent to itself;
When an adjacent search packet for searching for the wireless relay device as a connection destination among a plurality of the wireless relay devices is received from the wireless communication device, the index value of the wireless relay device adjacent to its own index value A response waiting time calculating means for calculating a response waiting time until a response packet for the adjacent search packet is transmitted, and
A wireless relay program that functions as a response packet transmission unit that transmits the response packet to the wireless communication apparatus after the response waiting time calculated by the response waiting time calculation unit has elapsed.

Images